40. Continuance of survey operations and rates in force at commencement of Act. Notwithstanding anything contained in this Chapter, all survey operations commenced under any law for the time being in force and continuing at the commencement of this Act shall be deemed to have been commenced and to be continuing under the provisions of this Chapter, and all revenue- rates in force at such commencement shall be deemed to have been determined and introduced in accordance with the provisions of this Chapter and shall remain in force until the introduction of revised revenue- rates; and such revised revenue- rates may be introduced at any time, notwithstanding anything contained in section 37.